Dented expansion chamber...

[Jmoozy27]

How bad does a dented expansion chamber effect performance??? It's an aftermarket pipe on what I expect to be primarily stock motor. I plan on finding another pipe but I want to use this one for now. Does it make tuning the motor difficult?

[onformula1]

Pics would help, but it depends on where it is and how bad.

I have seen them hurt, help and make zero difference.

Why don't you just blow it out?

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[3WW Star-John_Neary]

Depends but really should have no effect if its well past the head pipe. If you remember the Yamaha factory GP Yz490's ran what they called a "pancake pipe" to allow more air flow and it ran just fine.

[yaegerb]

Send it to me. I will get 90% if not all of it out. PM me if interested.

[Jmoozy27]

Its actually a few dents. Blow it out??? With compressed air???

yaegerb- I will attempt to fix it myself before outsourcing. I will definitely keep you in mind though. I'm kinda looking for a few DIY pointers and tips.

[yaegerb]

Yep I would blow it out while using MAPP. I bought all the tools to do so a few years ago. Done a few pipes for guys and a couple of my own with great success.

[Jmoozy27]

MAPP??? Might I ask what MAPP is???

[Jmoozy27]

Do you mean a small LPG torch? Because I have on of those.

[yaegerb]

MAPP gas. It's in the yellow container at Home Depot or lowes. Burns hotter than propane.

[onformula1]

First, yaegerb special thanks for offering a forum member with your service, once again showing why you are a true asset to this forum and the trike world.

Since you stated- "I'm kinda looking for a few DIY pointers and tips."

This it what I built in high school in 1992 and it still works great, I also built a pressure gauge, drain valve and hook on chuck manifold, but you don't need to spend money on that.

These are expandable plumbing plugs (The small ones) that fit in the stinger and tighten down, I have different sizes for different bikes.

The large plugs are used as temporary engine block freeze plugs and come in different sizes. Note- You drill through these plugs and put a motorcycle, trike or quad valve stem cut out of a old tube through the hole, the whole stem get coated with Automotive Goop or similar sealer, then tighten it down with the nut that comes with the old tube.

For extra safety I screw together two hose clamps 180 degrees from each other and clamp the pipe 3" away from the plug and safety wire the plug to the hose clamps. (I have never had one blow, but you never know)

Pressurize the pipe to 15 PSI, it does not take much, as the dents come out the pressure will go down so just refill it.

I have seen some guys use 50 PSI but I get them out with much less pressure.

Now heat the out edge of the dent in a circle moving slowly toward the center of the dent. The dents will come out like magic.

Really, really bad dents should be pulled out with a nut welded to the pipe and use a slide or better a electric welded dent puller, I have a cheap Harbor Freight one that is pretty nice.

Use a MAPP gas torch to heat the pipe, just put a MAPP gas bottle on your propane setup. Propane is old school, MAPP is better for everything IMHO.

Propane can't even cook a good steak.

The big dent on the backside is from the factory for clearance, don't pull it out or the pipe won't fit correctly, and yes it is ugly and gets
hit with a ball ping , but it's been done like that for ages.

[onformula1]

Also really bad dents are fixed by cutting the pipe in half in the center of the dent with a band saw, then straightened with a , anvil and mandrel.

Then you weld it back together in the correct spot, the pipe will be a band saw blade shorter but will still fit the pipe mounts in most cases.

Grind that PC tab off to get it out of the way, sand down the pipe and spray it with VHT exhaust paint, follow the instructions on the can and it will look much better than what you started with.

[barnett468]

How bad does a dented expansion chamber effect performance??? It's an aftermarket pipe on what I expect to be primarily stock motor. I plan on finding another pipe but I want to use this one for now. Does it make tuning the motor difficult?

Those dents in your photo ain't gonna make one single bit of difference as far as seat of the pants feel, but it would show up on a dyno . . been there done that WAY more times than i can count because when i started racing motorcycles, there was no such thing as an up pipe and the pipes would get smashed on the bottom in nearly every race . . i got so tired of fixing mine every week that i just left it smashed in for a while and still won races with it.

i think dave miller was one of the first people to make an up pipe which was called a snail pipe and it fit cr125's . . a few of the local pros [which were basically AMA top 10 national riders] ran them . . they looked pretty odd and sounded a bit different than other pipes.

it will not really make tuning any harder either.

.

[barnett468]

Its actually a few dents. Blow it out??? With compressed air???

I will definitely keep you in mind though. I'm kinda looking for a few DIY pointers and tips.

Well heres the problem, the metal is actually stretched, especially just below the metal label so the only way to really get that perfect is to heat it and cool it with a wet rag from a bucket of cold water in certain areas . . the cooling actually shrinks the metal but it basically takes a metal working god to do this . . i know because , i am NOT one, but i know guys that are and have had them do work for me.

this leaves a couple other options in addition to the ones that have been mentioned . . one of those is to weld body pins on it then heat it up and pull it out with a slide hammar etc as much as possible.

the most common way is to cut it in half at the seam below the label then get a tapered metal working tool or anvil that has one attached and heat it up then stick t on the tool then carefully hammar it out by beating on the cooler outside edges of the dent . . its really kind of hard to explain put thats another option and is exactly what i would do.
.

[barnett468]

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POST EDIT BECAUSE I STILL HAVE NO EDIT BUTTON

oh...and i use a hammar with a bronze tip because it has a higher modulus of elasticity than delrin....plus they use it for landing gear bushings for 747'S

[onformula1]

Jason, you didn't happen to get the stock pipe on that deal did you?